Increasing Sampling Interval in Cerebral Perfusion CT: Limitation for the Maximum Slope Model

Kloska, Stephan P.; Fischer, Tobias; Sauerland, Cristina; Buerke, Boris; Dziewas, Rainer; Fischbach, Roman; Heindel, Walter

doi:10.1016/j.acra.2009.07.009

« Previous Next »Academic Radiology
Volume 17, Issue 1 , Pages 61-66, January 2010

Increasing Sampling Interval in Cerebral Perfusion CT:

Limitation for the Maximum Slope Model

Stephan P. Kloska, MD
- Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
- Address correspondence to: S.P.K.
Tobias Fischer, MD
- Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
Cristina Sauerland, MSc
- Department of Medical Informatics and Biomathematics, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
Boris Buerke, MD
- Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
Rainer Dziewas, MD
- Department of Neurology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
Roman Fischbach, MD
- Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany
- Department of Radiology, Neuroradiology, and Nuclear Medicine, Asklepios Clinic Altona, Hamburg, Germany
Walter Heindel, MD
- Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Münster, Germany

Received 14 June 2009; accepted 13 July 2009. published online 07 September 2009.

Rationale and Objectives

The aim of this study was to evaluate increased sampling intervals on cerebral dynamic perfusion computed tomographic (PCT) imaging calculated using software relying on the maximum slope model.

Materials and Methods

PCT data sets from 32 patients with suspected acute stroke were acquired with a sampling interval of 1 image/s. The PCT data sets were modified to simulate sampling intervals of 2, 3, and 4 seconds. Maps of cerebral blood flow (CBF), cerebral blood volume, and time to peak (TTP) were calculated using software relying on the maximum slope model. Parenchymal and vascular peak enhancement; absolute values of CBF, cerebral blood volume, and TTP in the nonischemic hemisphere; and ischemic area in the different perfusion maps were measured.

Results

Parenchymal peak enhancement of the nonischemic hemisphere was statistically significantly decreased in all simulated data sets with >1-second sampling intervals (P < .001). Absolute CBF and TTP values in the nonischemic hemisphere were increased in all simulated data sets with >1-second sampling intervals (P = .044–.001 and P = .008–.001, respectively). The ischemic area was significantly underestimated for CBF and TTP in all simulated data sets with >1-second sampling intervals (P = .022–.005 and P = .019–.005, respectively).

Conclusions

Sampling intervals of >1 second on PCT imaging calculated using software relying on the maximum slope model significantly alter absolute CBF and TTP values and the size of ischemia in CBF and TTP. Thus, increasing the sampling interval on dynamic PCT imaging cannot be recommended in combination with this algorithm.

Key Words: Computed tomography, perfusion, stroke, sampling interval, maximum slope